Turbomachines such as aircraft engines generally have at least one adjustable row of guide blades on the compressor side, having a plurality of guide blades which are pivotable about their vertical axis, for setting optimal operating conditions. The row of guide blades together with a stationary inner ring which surrounds a rotor section forms a so-called guide blade ring. The inner ring is used for internal bearing of the guide blades, and has a plurality of radial openings for accommodating one journal bearing in each case on the blade side. It is proposed in DE 10 2006 024 085 A1 to form the inner ring from at least two semicircular ring segments having openings which are undivided in the axial direction and thus closed on the peripheral side, and to individually roll the ring segments over the journal bearings of the rotor blades mounted in housing halves. For this purpose, the ring segments are pretensioned to a constant clamping radius, positioned in the region of the journal bearings, and then relaxed. The inner ring, i.e., the guide blade ring, is uninstalled in a similar manner. The deformation and positioning of the inner ring segments is carried out with the aid of a clamping device disclosed in DE 10 2009 004 934 A1. However, special geometric and topological conditions of the inner ring and the guide blades must be maintained to allow this type of installation and deinstallation.